I. Field of the Invention
This invention relates to a water soluble drip stop plug for stopping dripping or water flow in a pipe and for dissolving after a predetermined time after water flow is restored to permit unimpeded flow, and more particularly to a cup shaped water soluble drip stop plug which has a unique configuration to allow for dissolution at various predetermined times.
II. Description of Related Art
A number of prior art patents have recognized the desirability of shutting off the flow of water in a pipe to permit repairs to be made. U.S. Pat. No. 4,357,960 issued to Han on Nov. 9, 1982, entitled Plumbing Method And Composition For Use In Same discloses the use of plugs of water soluble alginate into the open ends of a pipe to allow a repair to be made, after which the alginate dissolves, allowing water flow to be restored.
U.S. Pat. No. 4,003,393 issued to Jaggard on Jan. 18, 1977, entitled Gel-Like Composition for Use as a Pig in a Pipeline discloses the use of a gel-like composition as a pig or blockage in a pipeline. The gel-like mass is disclosed as a hydrocarbon liquid gel with a metal salt. The pig is used to separate the fluids in a conduit by introducing the gel between the flowing fluids. U.S. Pat. No. 3,631,870 issued to Livingston on Jan. 4, 1972, entitled Method of Stopping Flow in a Pipeline also discloses a method of arresting the flow of liquid in a pipeline so the pipeline can be repaired by transforming the flowing liquid into a gel to form a plug of material which stops flow downstream. U.S. Pat. No. 3,338,499 issued to Gilbert on Aug. 29, 1967, entitled Device for Welding Pipe Ends discloses the use of water soluble plastic plugs to seal the ends of two pipes in order to allow them to be welded. After the repair is made, the plastic plugs are dissolved by flushing with water.
All of the foregoing plugs and methods have some or all of the following limitations or disadvantages:
1. The plugs are not designed for dissolving at a predetermined period of time after water is restored.
2. The plugs are not designed to have the end break away prior to dissolution of the sides.
3. The plugs have a large indeterminate volume of material which needs to be purged from the pipe.